The invention relates to a pump the, which can be electrohydraulically adjusted. Such pumps, in particular axial, radial piston or vane cell pumps, are known in many embodiments and are employed in many different areas of use in hydraulic engineering. In connection with this, the main advantages of the electrohydraulic adjustment of these pumps are the rapid and precise electrical controllability and the low losses of the drive constructed by means of them because of the absence of expensive valves between the pump and the consumer. In this case the control pistons of the pumps are charged with a pressure medium via a control valve. The value which is decisive for pump adjustment or pump traverse, the eccentricity of the lifting ring in connection with radial piston pumps and vane cell pumps or, in connection with axial piston pumps, the pivot angle of the swash plate, is picked up by means of a displacement transducer. This actual value signal from the displacement transducer, which is proportional to the amount conveyed by the pump, is supplied to an electronic servo amplifier and is compared there with the set value provided there. At the same time the actual value of the valve adjustment is provided via a displacement transducer to this servo amplifier, which triggers the control valve. Control of the control valve or of the pump can be provided here via an interior pressure or an exterior pressure supply.
With electrohydraulically adjustable pumps of this type the adjustment member (for example the lifting ring or the swash plate) becomes dependent on the hydraulic clamping of the adjustment manner. Noise generation increases with a falling rigidity of the hydraulic clamping and is caused by the portions of the drive gear forces acting in the direction of the adjustment. Depending on the rigidity of the clamping, this results in a more or less strong excursion of the entire drive gear in accordance with the rhythm of the pistons or chambers entering and exiting the pressure chamber of the pump.